ISO 15512:2019 塑料 含水量的测定

标准编号：ISO 15512:2019

中文名称：塑料 含水量的测定

英文名称：Plastics — Determination of water content

发布日期：2019-05

标准范围

本文件规定了粉末、颗粒和成品形式塑料的含水量测定方法。这些方法不测试ISO 62测量的塑料吸水率（动力学和平衡）。方法A适用于低至0.1%的含水量测定，准确度为0.1%。方法B和方法C适用于低至0.01%的含水量测定，准确度为0.01%。方法D适用于低至0.01%的含水量测定，准确度为0.01%。方法E适用于低至0001%的水含量测定，准确度为0001%。所述准确度是检测限，也取决于最大可能样品质量。水含量表示为水的百分比质量分数。方法D适用于聚酰胺（PA）、聚碳酸酯（PC）、聚丙烯（PP）、聚乙烯（PE）、环氧树脂、聚对苯二甲酸乙二醇酯（PET）、聚酯、聚四氟乙烯（PTFE）、聚氯乙烯（PVC）、聚乳酸（PLA）、聚酰胺二胺（PAI），尤其不建议用于可释放NH3的样品。方法A、B、C和E通常适用于所有类型的塑料和湿度等级。含水量是加工材料的一个重要参数，预计将保持在适当材料标准规定的水平以下。本文件规定了六种替代方法。-方法A是一种使用无水甲醇的萃取方法，然后对萃取水进行卡尔费休滴定。它可用于所有塑料，适用于小于4mm×4mm×3mm的颗粒。该方法也可用于不溶于甲醇的粉末形式的预聚物材料。-方法B1是一种使用管式烘箱的蒸发方法。将试样中所含的水蒸发，并通过干燥空气或氮气载气输送至滴定池，然后通过收集水的水分传感器进行卡尔费休滴定或库仑测定。它可用于所有塑料，适用于小于4mm×4mm×3mm的颗粒。-方法B2是一种使用加热样品瓶的蒸发方法。将试样中的水蒸发，并通过干燥空气或氮气载气输送至滴定池，然后对收集的水进行卡尔·费歇尔滴定。它可用于所有塑料，适用于小于4mm×4mm×3mm的颗粒。-方法C是一种测压方法。水分含量由压力增加确定，压力增加是水分在真空下蒸发的结果。本方法不适用于含有挥发性化合物（水除外）的塑料样品，其含量对室温下的蒸汽压力有显著影响。应定期检查是否存在大量挥发性化合物，例如通过气相色谱法。对于新类型或等级的材料，尤其需要进行此类检查。-方法D是一种使用五氧化二磷（P2O5）电池检测汽化水的热库仑法。将试样中所含的水蒸发，并通过干燥空气或氮气载气输送至传感器单元，然后对收集的水进行库仑测定。本方法不适用于含有挥发性化合物（水除外）的塑料样品，其含量对室温下的蒸汽压力有显著影响。这与可与二磷五氧化二磷传感器酸性涂层反应的挥发性成分有关，例如氨或任何种类的胺。应定期检查是否存在大量挥发性化合物。对于新类型或等级的材料，尤其需要进行此类检查。-方法E是基于氢化钙的方法。由于真空和加热的结合，样品中的水分会蒸发。蒸发的水与氢化钙反应生成氢分子和氢氧化钙。氢使真空中的压力增加，与蒸发的水成正比。不与冷却阱中的氢化钙冷凝液反应且不影响测量的挥发性成分。

This document specifies methods for the determination of the water content of plastics in the form of powder, granules, and finished articles. These methods do not test for water absorption (kinetics and equilibrium) of plastics as measured by ISO 62.Method A is suitable for the determination of water content as low as 0,1 % with an accuracy of 0,1 %. Method B and Method C are suitable for the determination of water content as low as 0,01 % with an accuracy of 0,01 %. Method D is suitable for the determination of water content as low as 0,01 % with an accuracy of 0,01 %. Method E is suitable for the determination of water content as low as 0,001 % with an accuracy of 0,001 %. The stated accuracies are detection limits which depend also on the maximal possible sample mass. The water content is expressed as a percentage mass fraction of water.Method D is suitable for polyamide (PA), polycarbonate (PC), polypropylene (PP), polyethylene (PE), epoxy resin, polyethylene terephthalate (PET), polyester, polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polylactide (PLA), polyamidimid (PAI), it is especially not recommended for samples which can release NH3. Methods A, B, C and E are generally suitable for all types of plastic and moisture level.Water content is an important parameter for processing materials and is expected to remain below the level specified in the appropriate material standard.Six alternative methods are specified in this document.— Method A is an extraction method using anhydrous methanol followed by a Karl Fischer titration of the extracted water. It can be used for all plastics and is applicable to granules smaller than 4 mm × 4 mm × 3 mm. The method can also be used for, e.g. prepolymer materials in the form of a powder that are insoluble in methanol.— Method B1 is a vaporization method using a tube oven. The water contained in the test portion is vaporized and carried to the titration cell by a dry air or nitrogen carrier gas, followed by a Karl Fischer titration or a coulometric determination by means of a moisture sensor of the collected water. It can be used for all plastics and is applicable to granules smaller than 4 mm × 4 mm × 3 mm.— Method B2 is a vaporization method using a heated sample vial. The water contained in the test portion is vaporized and carried to the titration cell by a dry air or nitrogen carrier gas, followed by a Karl Fischer titration of the collected water. It can be used for all plastics and is applicable to granules smaller than 4 mm × 4 mm × 3 mm.— Method C is a manometric method. The water content is determined from the increase in pressure, which results when the water is evaporated under a vacuum. This method is not applicable to plastic samples containing volatile compounds, other than water, in amounts contributing significantly to the vapour pressure at room temperature. Checks for the presence of large amounts of volatile compounds are to be carried out periodically, for example by gas chromatography. Such checks are particularly required for new types or grades of material.— Method D is a thermocoulometric method using a diphosphorus pentoxide (P2O5) cell for the detection of the vaporized water. The water contained in the test portion is vaporized and carried to the sensor cell by a dry air or nitrogen carrier gas, followed by a coulometric determination of the collected water. This method is not applicable to plastic samples containing volatile compounds, other than water, in amounts contributing significantly to the vapour pressure at room temperature. This is specially related to volatile components which can react with the acidic coating of the diphosphorus pentoxide sensor, e.g. ammonia or any kind of amines. Checks for the presence of large amounts of volatile compounds are to be carried out periodically. Such checks are particularly required for new types or grades of material.— Method E is a calcium hydride based method. The water content of a sample evaporates due to a combination of vacuum and heating. The evaporated water reacts with calcium hydride to molecular hydrogen and calcium hydroxide. The hydrogen causes an increase of pressure in the vacuum that is proportional to the evaporated water. Volatile components, that do not react with calcium hydride condensate in a cooling trap and do not affect the measurement.

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